Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
#define ll long long

char s[100][101];
int h,w;
bool vis[101][101];

struct node
{
    int x,y,v;
    node(){}
    node(int x,int y,int v):x(x),y(y),v(v){}
};
int fx[]={1,-1,0,0};
int fy[]={0,0,1,-1};

int main()
{
    cin>>h>>w;
    for(int i=0;i<h;i++)cin>>s[i];

    int white = 0;
    for(int i=0;i<h;i++)
        for(int j=0;j<w;j++)if(s[i][j]=='.')white++;

    queue<node> q;
    q.push(node(0,0,0));
    int ans=-1;
    while(!q.empty())
    {
        node now = q.front();
        q.pop();
        for(int i=0;i<4;i++)
        {
            int x=now.x+fx[i],y=now.y+fy[i];
            if(x<0||x==h||y<0||y==w||vis[x][y]||s[x][y]=='#')continue;
            if(x==h-1&&y==w-1)
            {
                return cout<<white-now.v-2,0;
            }
            vis[x][y]=1;
            q.push(node(x,y,now.v+1));
        }
    }
    cout<<"-1";
    return 0;
}